Jamie Payton

The impact of component architectures on interoperability

Component interoperability has become an important concern as companies migrate legacy systems, integrate COTS products, and assemble modules from disparate sources into a single application. While middleware is available for this purpose, it often does not form a complete bridge between components and may be inflexible as the application evolves. What is needed is the explicit design information that will forecast a more accurate, evolvable, and less costly integration solution implementation.Emerging research has shown that interoperability problems can be traced to the software architecture of the components and integrated application. Furthermore, the solutions generated for these problems are guided by an implicit understanding of software architecture. Current technology does not fully identify what must be made explicit about software architecture to aid in comparison of the architectures and expectations of participating entities within the integrated application. Thus, there can be no relief in the expense or the duration of implementing long-term reliance on middleware. The overall goal of our research is to extract and make explicit the information needed to define and build this technology. This paper focuses on identifying, classifying, and organizing characteristics that help to define an architectural style by using abstraction and semantic nets. We illustrate the relationships between the characteristics and their relevance to interoperability via examples of integrated applications.

Incentive Mechanisms for Participatory Sensing: Survey and Research Challenges

Participatory sensing is a powerful paradigm that takes advantage of smartphones to collect and analyze data beyond the scale of what was previously possible. Given that participatory sensing systems rely completely on the users’ willingness to submit up-to-date and accurate information, it is paramount to effectively incentivize users’ active and reliable participation. In this article, we survey existing literature on incentive mechanisms for participatory sensing systems. In particular, we present a taxonomy of existing incentive mechanisms for participatory sensing systems, which are subsequently discussed in depth by comparing and contrasting different approaches. Finally, we discuss an agenda of open research challenges in incentivizing users in participatory sensing.

A Formal Treatment of Context-Awareness

Context-aware computing refers to a computing paradigm in which the behavior of individual components is determined by the circumstances in which they find themselves to an extent that greatly exceeds the typical system/environment interaction pattern common to most modern computing. The environment has an exceedingly powerful impact on a particular application component either because the latter needs to adapt in response to changing external conditions or because it relies on resources whose availability is subject to continuous change. In this paper we seek to develop a systematic understanding of the quintessential nature of context-aware computing by constructing a formal model and notation for expressing context-aware computations. We start with the basic premise that, in its most extreme form, context should be made manifest in a manner that is highly local in appearance and decoupled in fact. Furthermore, we assume a notion of context that is relative to the needs of each individual component, and we expect context-awareness to be maintained in a totally transparent manner with minimal programming effort. We construct the model from first principles, seek to root our decisions in these formative assumptions, and make every effort to preserve minimality of concepts and elegance of notation.

Modeling adaptive behaviors in Context UNITY

Context-aware computing refers to a paradigm in which applications sense aspects of the environment and use this information to adjust their behavior in response to changing circumstances. In this paper, we present a formal model and notation (Context UNITY) for expressing quintessential aspects of context-aware computations; existential quantification, for instance, proves to be highly effective in capturing the notion of discovery in open systems. Furthermore, Context UNITY treats context in a manner that is relative to the specific needs of an individual application and promotes an approach to context maintenance that is transparent to the application. In this paper, we construct the model from first principles, introduce its proof logic, and demonstrate how the model can be used as an effective abstraction tool for context-aware applications and middleware.

Coordination middleware supporting rapid deployment of ad hoc mobile systems

This paper addresses the design and implementation of thin coordination veneers for use in the development of applications over ad hoc wireless networks. A coordination veneer is defined as an adaptation layer that customizes a general-purpose coordination middleware to a particular domain with minimal development effort. This technique allows developers to build highly-tailored coordination models while leveraging established models and middleware. We present three such veneers, the coordination models they embody, and the manner in which they were implemented The LIME middleware, which supplies tuple space based coordination in the ad hoc environment, serves as the implementation base for our veneers. These veneers cover diverse areas in ad hoc mobility: service discovery and provision, event registration and distribution, and secure tuple space access.

A notation for problematic architecture interactions

The progression of component-based software engineering (CBSE) is essential to the rapid, cost-effective development of complex software systems. Given the choice of well-tested components, CBSE affords reusability and increases reliability. However, applications developed according to this practice can often suffer from difficult maintenance and control, problems that stem from improper or inadequate integrate solutions. Avoiding such unfortunate results requires knowledge of what causes the interoperability problems in the first place. The time for this assessment is during application design. In this paper, we define problematic architecture interactions using a simple notation with extendable properties. Furthermore, we delineate a multi-phase process for pre-integration analysis that relies on this notation. Through this effort, potential problematic architecture interactions can be illuminated and used to form the initial requirements of an integration architecture.

Reasoning About Context-Awareness in the Presence of Mobility

Context-awareness is emerging as an important computing paradigm designed to address the special needs of applications that must accommodate or exploit the highly dynamic environments that occur in the presence of physical or logical mobility. A number of formal models are available for reasoning about concurrency. Models designed to capture the specifics of mobility are fewer but still well represented (e.g., Mobile Ambients, -Calculus, and Mobile UNITY). These models do not, however, provide constructs necessary for explicit modeling of context-aware interactions. This paper builds upon earlier eorts on state-based formal reasoning about mobility and explores the process by which a model such as Mobile UNITY can be transformed to explicitly capture context-awareness. Starting with an examination of the essential features of context-aware systems, this paper explores a range of constructs designed to facilitate a highly decoupled style of programming among context-aware components. The result of this exploration is a model called Context UNITY.

Automatic consistency assessment for query results in dynamic environments

Queries are convenient abstractions for the discovery of information and services, as they offer content-based information access. In distributed settings, query semantics are well-defined, e.g., they often satisfy ACID transactional properties. In a dynamic network setting, however, achieving transactional semantics becomes complex due to the openness and unpredictability. In this paper, we propose a query processing model for mobile ad hoc and sensor networks suitable for expressing a wide range of query semantics; the semantics differ in the degree of consistency with which results reflect the state of the environment during execution. We introduce several distinct notions of consistency and formalize them. A practical contribution of this paper is a protocol for query processing that automatically assesses and adaptively provides an achievable degree of consistency given the state of the operational environment throughout its execution. The protocol attaches an assessment of the achieved guarantee to returned query results, allowing precise reasoning about a query with a range of possible semantics.

Semantic self-assessment of query results in dynamic environments

Queries are convenient abstractions for the discovery of information and services, as they offer content-based information access. In distributed settings, query semantics are well-defined, for example, queries are often designed to satisfy ACID transactional properties. When query processing is introduced in a dynamic network setting, achieving transactional semantics becomes complex due to the open and unpredictable environment. In this article, we propose a query processing model for mobile ad hoc and sensor networks that is suitable for expressing a wide range of query semantics; the semantics differ in the degree of consistency with which query results reflect the state of the environment during query execution. We introduce several distinct notions of consistency and formally express them in our model. A practical and significant contribution of this article is a protocol for query processing that automatically assesses and adaptively provides an achievable degree of consistency given the operational environment throughout its execution. The protocol attaches an assessment of the achieved guarantee to returned query results, allowing precise reasoning about a query with a range of possible semantics. We evaluate the performance of this protocol and demonstrate the benefits accrued to applications through examples drawn from an industrial application.

Integrating participatory sensing in application development practices

With the widespread capabilities of commodity mobile devices, applications will increasingly incorporate participatory sensing functionality. Participatory sensing directly involves end-users in collecting (and ultimately sharing) information about the environment. Applications that rely on participatory sensing range from those that simply enable information sharing, to environmental monitoring and response, and route and behavior planning. As more and more applications demand the incorporation of participatory sensing, it becomes imperative to create software architectures, design patterns, and programming libraries that enable the integration of participatory sensing with software engineering theory and practice. In this position paper, we explore the new challenges that participatory sensing applications present, specifically focusing on challenges that demand a reevaluation of software engineering design principles, tools, and techniques. For these challenges, we also posit possible ways forward.